1. Field of the Invention
The present invention relates to an image processing method and an image processing device at the time of outputting image data to an output device which forms, on a recording sheet, an image corresponding to image data for multicolor printing. More specifically, the present invention relates to an image processing method and an image processing device for image data or image-drawing commands which include spot colors which are different than process colors.
2. Description of the Related Art
DTP (desktop publishing) is becoming increasingly popular as a digital method in the field of printing processing. In DTP, a page layout is prepared by carrying out image creation, manipulation, editing, and the like at a processing device such as a personal computer, a work station, or the like. On the basis of this page layout, a film for exposing a printing plate is prepared (CEPS), or image data is directly written to a printing plate in order to prepare a printing plate for printing (CTP: Computer to Plate).
When proofing or the like is carried out before printing by using the actual printing plate, the page layout displayed on a monitor is printed-out by a print-out device such as a page printer or the like by using a WYSIWYG function or the like.
On the other hand, usual color printing is carried out by using the four colors (process colors) of cyan, magenta, yellow, and black. However, there are cases in which color printing is carried out by using, as needed, inks of colors (hereinafter, “spot colors”) which are different than the process colors. Further, in order to keep printing costs down, there are cases in which two-color printing is carried out. In such cases, special effects may be obtained by using one color among the process colors and a spot color, or by using spot colors for the two colors.
In current applications for DTP, combinations of a spot color and a spot color, or of a spot color and a process color, cannot be designated easily. Therefore, the data for two-color printing is generally output onto films by using two process colors, and printing is carried out by using an ink of a color different than a process color (i.e., a spot color) on the two printing plates which have been obtained as a result.
On the other hand, only outputs in process colors can be obtained in printing simulations for such image data. Therefore, it is difficult to clearly confirm how the actual printed matter will turn out.
Thus, it is known to provide a following method of carrying out spot color printing simulation: a color chart is printed by actually using a printing plate, by using the predetermined spot color ink used in the two-color printing. By measuring this color chart, a profile for the spot color (a CMYK—L*a*b* look-up table) is created. By using this profile for the spot color and a profile for the printer (a L*a*b*—C′M′Y′K′ look-up table), CMYK—C′M′Y′K′ conversion using a color management function is realized, and the simulation of spot color printing is thereby carried out.
Moreover, it is known to provide a method of outputting a color comprehensive layout by replacing the respective colors of a document, which is prepared by using for example any two colors among C, M, Y, K, by desired ink colors (spot colors).
However, printing simulations using spot colors can only address the substitution of a spot color with respect to a process color plate. However, there are cases in which a document, which includes an object using a spot color, is prepared, and the object of the spot color cannot be replaced by another spot color in the processes of design and examination.